Coin hopper measurement and control system

ABSTRACT

The present invention provides a weighing apparatus for weighing coins accumulated in a coin hopper using a load cell and automatically taking a periodic readings of the number of coins accumulated in the hopper. By periodically monitoring the hopper and automatically calculating the number of coins in the hopper, theft of coins and other irregularities can be easily and timely detected. The unauthorized removal of coins during an actual or purported maintenance procedure can be detected by automatically determining a count of coins before a hopper access door is opened, automatically counting the number of coins once the door is closed, and using those two counts to determine the change in the number of coins in the hopper at the time of the change. In a preferred embodiment, the identity of the person opening the hopper door and the time in which the hopper door is opened and closed are recorded, along with any detected discrepancy between the change in coin count and an expected change, if any, in coin count.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.08/414,238, filed Mar. 31, 1995, which is incorporated herein byreference for all purposes. Applicant also claims priority from the U.S.Provisional Patent application entitled "Coin Hopper Measurement andControl System" (Application No. 60/005,312) filed Oct. 16, 1995. Thatapplication is incorporated herein by reference for all purposes.

A U.S. patent application entitled "KEJO Coin Hopper" (Application No.08/444,560) filed May 19, 1995 now abandoned and a provisional patentapplication entitled "Improved Coin Hopper" (Application No. 60/005,298)filed Oct. 16, 1995 are incorporated herein by reference for allpurposes.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the xerographic reproduction by anyone of the patentdocument or the patent disclosure in exactly the form it appears in thePatent and Trademark Office patent file or records, but otherwisereserves all copyright rights whatsoever.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to hoppers used to collect and distributecoins in gaming and vending machines. More particularly, the presentinvention relates to a coin hopper which is reliable, effectivelytamperproof and easily assembled.

BACKGROUND OF THE INVENTION

The present invention relates to the field of coin or disk handling.More specifically, in one embodiment the invention provides an improvedmethod and apparatus for controlling coin and disk accounting in slotmachines and other gaming machines.

Because casinos deal with large amounts of cash, they are subject totheft by dishonest persons and are particularly vulnerable to theft bydishonest employees. If so inclined, a dishonest technician can take afew coins from each casino slot machine as it is serviced. Although thetake over time and over many technicians can be quite large, since eachindividual take is so small, casinos have resigned themselves to beingshorted and treat the thefts as a cost of doing business. Casinos havetried to combat this problem by assigning two or more technicians toeach task requiring an open gaming machine. However, this leads toadditional labor costs and doesn't help if each of the assignedtechnicians is dishonest.

An alternate solution is to seal the coin or bill reservoir so that onlytrusted money-handling employees working in a cashier's cage can get tothe coins or bills. Coin acceptors are more difficult to seal than billacceptors because coin acceptors have to give out coins as well asreceive them, whereas bill acceptors simply store the bills, and becausecoins are more likely to jam a hopper than pliable bills. If jamming wasnot a concern, then the hoppers could be sealed. However, where jammingis a possibility, sealing the hoppers might result in greater down-timefor the gaming machines, which is a loss to the casinos which can begreater than the theft loss.

The co-filed provisional patent application (App. Ser. No. 60/005,298)referred to above describes an improved hopper which is much less likelyto jam than prior art hoppers. However, even with a jam-free hopper, thehopper must be occasionally opened to refill with coins after a jackpotis hit and thus is not readily amenable to being sealed. Even if thehopper were sealed, it would not prevent a coin loader from removingsome coins from the load of coins being added to the hopper.

As should be apparent after reading the above, merely counting coins asthey go into the hopper and counting coins as they leave the hopperwould not prevent theft, as a physical inventory would only indicatethat coins are missing, not who took them.

Prior art systems exist for weighing coins to count the coins, and manysuch devices might be used in a money room of a casino. For example,U.S. Pat. No. 5,193,629 issued to Lare and U.S. Pat. No. 4,512,428issued to Bullivant describe apparatus for weighing coins. While suchweighing devices might be suitable for weighing coins in a money room,it is unsuitable in a gaming machine environment, where the hoppers mustbe enclosed to prevent theft by players, as well as being remotelyaccessible, operable in an electrically noisy and vibration-proneenvironment and able to detect theft at the time of the theft.

From the above it is seen that an improved method and apparatus for coinaccounting and theft prevention is needed.

SUMMARY OF THE INVENTION

The present invention provides a weighing apparatus for weighing coinsaccumulated in a coin hopper using a load cell and automatically takinga periodic readings of the number of coins accumulated in the hopper. Byperiodically monitoring the hopper and automatically calculating thenumber of coins in the hopper, theft of coins and other irregularitiescan be easily and timely detected. The unauthorized removal of coinsduring an actual or purported maintenance procedure can be detected byautomatically determining a count of coins before a hopper access dooris opened, automatically counting the number of coins once the door isclosed, and using those two counts to determine the change in the numberof coins in the hopper at the time of the change. In a preferredembodiment, the identity of the person opening the hopper door and thetime in which the hopper door is opened and closed are recorded, alongwith any detected discrepancy between the change in coin count and anexpected change, if any, in coin count. An expected change, for example,would exist when a technician is asked to open the machine and removecoins (which are later counted). The number of coins in the hopper atany given time is determined from the combined weight of the hopper andthe coins accumulated in the hopper. During a calibration process, atare (zero) weight of the hopper is determined, and an operator is giventhe opportunity to have a per coin weight determined automatically byplacing a known quantity of coins in the hopper and measuring thecombined weight and the known quantity of coins. Knowing the tare weightof the hopper and the per coin weight, the number of coins accumulatedin a hopper can be calculated from the combined weight of the hopperwith the coins accumulated therein.

A further understanding of the nature and advantages of the inventionsherein may be realized by reference to the remaining portions of thespecification and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a slot machine with its door open showing acoin hopper.

FIG. 2 is a more detailed side view of the coin hopper shown in FIG. 1illustrating the cantilevered mounting the hopper on the load cell.

FIG. 3 is a schematic diagram of the electronics of the coin hopper andaccounting system shown in FIG. 2.

FIG. 4 is a flowchart of an accounting process for accounting for coinsin a coin hopper such that theft is timely detected.

FIG. 5 is a flowchart of a process for automatically taking periodicmeasurements to determine a coin count of coins in the hopper.

FIG. 6 is a flowchart of a process for calibrating a hopper's tareweight and a per coin weight.

FIG. 7 is a flowchart of a process for obtaining an accurate hopperweight during calibration in the presence of noise and/or vibrations.

FIG. 8 is a flowchart of a process for obtaining an accurate coin countin the presence of noise and/or vibrations.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates how a coin hopper 10 is often mounted in a slotmachine 1. To show the placement of the hopper, a hopper door 2 of slotmachine 1 has been opened. During operation, the hopper door 2 wouldusually be locked shut to prevent theft of coins by players. As shownhere, hopper 10 is often placed below a coin insertion slot 3 and abovea coin payout tray 4. To initiate play of a game, a player would insertone or more coins into coin insertion slot 3 and those coins would dropinto hopper 10. Although not shown in FIG. 1, the coins would typicallypass through a coin handling unit on their way to hopper 10, where thecoin handling unit performs tests (size, weight, angular moment, etc.)to determine if the coin is real and of the proper denomination. Thecoin handling unit, or other device, would provide a signal, such as anelectric "coin in" pulse, to a logic board to signal that a valid coinhas been inserted. If a game is a winning game, or the player cashes outhis or her credits with slot machine 1, hopper 10 ejects the correctamount of coins from ejection slot 5 into payout tray 4. In someembodiments, such as so-called "slant-top" slot machines, the hopper isactually located below the payout tray and an "elevator" or "escalator"mechanism is used to raise the paid out coins higher than the payouttray so that the coins will fall into the payout tray, and thus beaccessible to the player.

Typically, a motorized conveyor assembly (not shown) of hopper 10 causescoins to be ejected to the payout tray or elevator and that conveyorassembly runs until a "coin out" counter signals that the correct numberof coins have been ejected. Thus, thefts can be detected by taking aninitial manual inventory of the coins in hopper 10, then tracking the"coin in" and "coin out" pulses and taking a closing inventory. However,this process requires two manual inventory steps, does not detect whotook the missing coins or when, and doesn't account for coins which aremisfed into or out of hopper 10 and fall into other areas inside slotmachine 1, such as area 8. To solve these problems, an electronic weightsensor, specifically a load cell 12, is provided as shown in FIG. 2.

FIG. 2 illustrates the mounting of hopper 10 onto a base 14 of slotmachine 1 using load cell 12 and cantilever spacers 16. Hopper 10 andthe coins therein are totally supported by cantilever spacer 16(a),which is in turn totally supported by load cell 12, which is turntotally supported by cantilever spacer 16(b) mounted directly to base14. Thus, the weight of the hopper and the coins therein is applied toload cell 12 causing a strain on load cell 12 which is a function of theweight of the hopper and coins therein. That strain is measured by astrain gauge 18 and the strain can be measured by reading electricalsignals on the lines of cabling 20. In a preferred embodiment, load cell12 is a 36 kilogram load cell sold by HBM, Inc. of Connecticut with asensor attached thereto manufactured by Cirrus Logic. For largerhoppers, a 72-kilogram load cell sold by HBM, Inc. can be used. Ofcourse, any suitable load cell can be used.

Referring now to FIG. 3, a schematic of a logic board 100 used in apreferred embodiment of the present invention is shown. In analternative embodiment, the role of the logic board is subsumed into acentral slot machine control system. The logic board comprises ananalog-to-digital converter (ADC) 102 coupled to load cell 12 to converta load signal from an analog signal to a digital load cell sample. Asshown, the digital load cell sample has a resolution of 14 bits (hencethe 14 signal lines carrying the signal in parallel), but otherresolution A/D converters can also be used. With 14 bits, an integercorresponding to the digital load cell sample can range from 0 to16,383. With proper calibration and proper selection of load cell 12, afully loaded hopper will cause a reading near the top end of the range,so as to have the best resolution.

ADC 102 provides its output to an input-output (I/O) controller 104which in turn provides samples, as requested, to a central processingunit (CPU) 106. CPU 106 executes programs stored in program memory 108and uses a variable memory 110 to store data incident to the executionof those programs. The programs executed by CPU 106 compriseinstructions for following the processes described in FIGS. 4-8, howeverCPU 106 might also execute other programs not described herein. In someembodiments, a CPU with built-in I/O control functions and/or memorymight be used, however the description of FIG. 3 still applies to suchintegrated systems.

FIG. 3 shows a number of I/O signals being provided to, or by, I/Ocontroller 104. For example, "Coin In" and "Coin Out" signals areprovided from coin handling devices. These signals can be pulses (onepulse per coin) or can be other signals indicating a count, as are wellknown in the art. I/O controller 104 might also provide motor, sound,reel, lights and display control signals, if CPU 106 or I/O controller104 are programmed to handle such functions of slot machine 1. I/Ocontroller 104 receives switch signals from a variety of sources, ofwhich a calibration switch 112, a start switch 114, a reset switch 116and a door switch 118 are shown. FIG. 3 also shows an internal display120 which is used as explained below.

Also shown in FIG. 3 is a drop box load cell 12(a) and an ADC 102(a)coupled to I/O controller 104. Drop box load cell 12(a) performs afunction similar to load cell 12, in that it provides an indication ofthe weight of a drop box (not shown) and the coins therein. A drop boxis a standard part of some slot machines, and is used to contain theoverflow of coins from a hopper. For example, in FIG. 1, a drop boxmight have been installed below hopper 10. A drop box is similar to ahopper, in that it holds a collection of coins, but differs from ahopper in that coins are not ejected from the drop box. If a drop box isused, a hopper may have a sensor which detects when the hopper is full(or could use the present invention to determine if more than athreshold number of coins are in the hopper), and ejects coins in suchas way that the ejected coins fall into the drop box instead of intopayout tray 4. Of course, load cell 12(a) and ADC 102(a) are not neededwhere coin accounting for drop box coins is done separately or the dropbox is not used.

I/O controller 104 also reads/writes data from a data pin 124 (seeFIG. 1) as explained below. In a preferred embodiment, data pin 124 ispart of a communication system manufactured by Dallas Semiconductor. Adata wand (not shown) is a hand-held, battery-powered device with aninternal computer which communicates with I/O controller 104 through asingle signal line and chassis ground connection.

In operation, load cells 12, 12(a) are provided with load cell powerfrom a load cell power source 122 and generate an analog voltage whichis a function of their load, which analog voltage is input to the loadcell's ADC 102 or 102(a). In operation, the states of the variousswitches shown in FIG. 3 are monitored, as explained in connection withFIG. 4.

FIG. 4 is a flowchart of a process for timely detecting unauthorizedcoin removal as performed by CPU 106 according to instructions stored inprogram memory 108. Each step in FIGS. 4-8 is numbered with a stepnumber and the step numbers within each figure follow in sequentialorder of execution of the steps, except where noted.

The process shown in FIG. 4 begins when hopper door 2 (see FIG. 1) isopened (S1). This process assumes that the primary mode of coin theft isfrom dishonest technicians or other casino employees opening slotmachine door 2 to perform actual or purported maintenance and takingcoins from hopper 10 while hopper door 2 is open. Presumably, a gamecannot be played and a payout cannot be made while door 2 is open andtherefore a coin count should not change except in cases of authorizedcoin withdrawal. In a preferred embodiment, hopper door 2 is secured byan electronic switch, such as a solenoid 126 (see FIG. 1), which canonly be activated by the technician or employee touching their assigneddata wand to data pin 124. As part of the opening process, CPU 106records an employee ID communicated from the data wand before activatingsolenoid 126 to open hopper door 2. Alternatively, hopper door 2 can beopened by an ordinary key and the door opening can be detected by doorswitch 118. In either case, a preferred embodiment records the time ofopening.

When hopper door 2 is being opened, or preferably just before access isgranted or hopper door 2 moves, a coin count is obtained (S2) and thecount is stored as the opening count (OC). If CPU 106 makes continuous,periodic readings, then the opening count might just be the most recentperiodic reading before hopper door 2 was opened and after the last gamewas played.

At step S4, the door is monitored until it is closed, and another coincount is taken (S5). In a preferred embodiment, this second coin countis a reading taken after slot machine 1 has stabilized following theclosing of the door. This coin count, C, is stored (S6) as the closingcount (CC). Next (S7), an expected change count (EC) is determined. Thisexpected change count is positive in the case where a technician is sentto a slot machine to add coins to a depleted hopper, is negative wherethe technician is sent to the slot machine to remove coins, and is zerowhere the technician is sent to the slot machine simply to performmaintenance. Of course, other variations of this scheme are alsopossible. For example, the expected change count might not be known atthe time the coins are removed, but later determined after thetechnician turns over the coins removed from the slot machine.

If the expected change count is known at the time the door is closed, adeficiency can be easily calculated (S8), by subtracting the closingcount (CC) from the opening count (OC) and adding the expected changecount (EC). If the resulting deficiency (D) is not equal to zero (S9),then an alarm can be set (S10). Where the slot machine does notautomatically determine the identification of the technician or otheremployee opening the slot machine, the setting of an alarm might resultin a flashing light on the slot machine being immediately activated, sothat the unauthorized removal of coins can be detected by a floormanager while the thief is still present at the machine. However, in apreferred embodiment, the slot machine detects the time of opening andclosing as well as the identification of the person opening the machine,thereby allowing the deficiency to be easily traced to a specificemployee. In an alternate embodiment, where the slot machine is not ableto determine the identity of the person opening the slot machine, theslot machine will merely record the time of entry and the deficiency forlater comparison to a log kept elsewhere showing which employees hadaccess to which slot machines at which times. In a preferred embodiment,the alarm is not merely a local alarm in the form of a flashing light onthe slot machine or the like, but is an alarm which is recorded by CPU106 and is communicated to a central security station (not shown).Regardless of whether an alarm is set or not, the flow of the processreturns to step S1, where it remains until the hopper door is againopened.

While the process shown in FIG. 4 will detect unauthorized removal ofcoins when a hopper door 2 is open, it does not necessarily detectunauthorized removal of coins when hopper door 2 is closed. The lattertype of unauthorized coin removal is less problematic than the former,since it would require that the dishonest employee or technician modifythe slot machine to eject or reroute coins out of the hopper 10 intoother spaces inside slot machine 1 for later retrieval. This manner oftheft can be counteracted by monitoring the rate at which coins fail toreach hopper 10 or fail to be counted as they are ejected. Withcentralized monitoring of slot machine activity, the unaccounted forloss of coins while hopper door 2 is closed can be monitored for eachslot machine and those slot machines with higher than normal rates ofcoin loss can be carefully inspected for modifications which increasesuch coin loss. Coin loss from the hopper to the drop box during normaloperation can be accounted for through the use of load cell 12(a) andADC 102(a), as described above.

In a preferred embodiment, the slot machine activity is communicated toa central security station for easy monitoring and prompt detection ofdeficiencies. The automatic coin accounting process of FIG. 4 is aprocess which can be run independently of the coin counting processesshown elsewhere. The use of the present invention to handle other modesof theft or coin accounting should be apparent after reading thispresent description.

While FIG. 4 shows a process of deficiency detection, FIG. 5 shows amore general process of taking a reading to calculate coin count C. In apreferred embodiment, the processes of FIG. 4 and the processes of FIG.5 run asynchronously, with the process shown in FIG. 5 being a processof periodically taking a reading to update the current coin count andstoring a new coin count whenever it is determined that a stable andreliable reading has been taken, while the process shown in FIG. 4 (morespecifically steps S2 and S5) merely refers to the stored coin countvalue for the latest reliable coin count.

Referring now to FIG. 5, the process shown therein begins with aninitialization of the variables used (S21). At this point, the operatoris prompted with "START" or a similar prompt, prompting the operator tobegin the calibration process. The prompt is displayed, in someembodiments, on a computer terminal, while in other embodiments it isdisplayed on an LED display 120 coupled to I/O controller 104 (see FIG.3). Preferably, the operator first determines that the hopper and slotmachine are stable and the hopper is empty.

At step S22, CPU 106 (see FIG. 3) determines whether diagnostics wererequested by the operator. One embodiment, the operator signals thatdiagnostics are requested by sending a predetermined signal from aterminal to I/O controller 104 such as through the data pin I/O or bysimultaneously pressing calibration button 112 and start button 114 (seeFIG. 3). If diagnostics are requested, CPU 106 executes thosediagnostics (S23) and proceeds to step S24. Otherwise, if diagnosticsare not requested, CPU 106 proceeds directly to step S24.

At step S24, CPU 106 checks to see if the operator has requested acalibration. In the embodiment shown in FIG. 3, the operator requestscalibration by pressing calibration button 112. If calibration isrequested, the calibration process is executed (S25) to determine a tareweight (TW) and a per coin weight (CW). Following the calibration step,which is described in further detail in FIG. 6, or if calibration is notrequested, CPU 106 proceeds to step S26, where it determines whether ornot the hopper was calibrated. If the hopper was not calibrated, eitherbecause calibration was not requested or because the calibration stepwas not successful due to unreliable readings, CPU 106 returns to stepS24, thus creating a loop that is only exited when the hopper is finallycalibrated.

When the loop is exited, CPU 106 proceeds to step S27, where a readingof the hopper weight is taken and a coin count is calculated. Thisprocess is shown in further detail in FIG. 8. Once a reliable coin countis obtained (S28), that coin count is displayed, transmitted to a remotestorage and/or display device or the coin count is simply stored invariable memory 110 (see FIG. 3), for later provision of a coin countvalue to other processes which use the coin count. Once the coin countis obtained and processed as described above, CPU 106 returns to stepS24. Thus, while the hopper remains calibrated, CPU 106 executes aperiodic loop of taking a reading, calculating a coin count, andproviding the coin count to various display or memory devices as needed.In a preferred embodiment, a latest reliable value for the coin count isretained and is not overwritten by any subsequent unreliable coincounts, thereby providing a reliable coin count value which can bepolled at any time by asynchronous processes.

FIG. 6 shows the calibration process of step S25 in further detail. Atthe outset of the calibration process, CPU 106 waits (S41) for acalibration signal, either from a remote device or from the operatorpressing calibration switch 112. If the calibration signal is notreceived within a predetermined time, the calibration process is abortedand an indication that calibration did not complete is given so thatreadings (see FIG. 5) will not be taken until the calibration processactually successfully completes. If the calibration signal is received,CPU 106 proceeds to obtain the hopper weight (S42), which is describedin further detail in FIG. 7. Prior to receipt of the calibration signal,the hopper should have been emptied by the operator so that a tareweight of the hopper can be obtained. Also, if the calibration signal issent using calibration switch 112, CPU 106 delays for a predeterminedtime to allow for dampening of slot machine vibrations due tocalibration switch 112 being pressed. If the hopper weighing processreturns an error indicating that a reliable hopper weight cannot beobtained, CPU 106 aborts the calibration process (S42). However, if areliable hopper weight is obtained, that hopper weight is stored as thenew tare weight (TW) value for the hopper (S44).

Once the hopper tare weight is obtained, CPU 106 waits for a COIN WEIGHTsignal (S45), and when the COIN WEIGHT signal is received, CPU 106 againmeasures the hopper weight (S47). Before the COIN WEIGHT signal is sent,the process expects that the hopper now contains N coins. In a preferredembodiment, N=20, however it should be apparent that other values of Ncould be used. If a time out occurs while waiting for the COIN WEIGHTsignal or the hopper weighing process returns an error, the calibrationprocess is aborted (S46) and only the tare weight is updated. Where ahopper is modified or moved to a different slot machine, the calibrationprocedure could be allowed to abort at step S46, without ill effects,since the prior per coin weight can be reused.

Once the hopper weight is obtained (S47) for the hopper and the N coins,a coin weight is calculated (S48) by subtracting the hopper tare weight(TW) from the just measured hopper weight (HW) and dividing thedifference by N. This new per coin weight (CW) is then stored (S49) invariable memory 110 and the calibration process returns indicating asuccessful hopper calibration.

FIG. 7 shows the process of getting a hopper weight, the result beingeither returning successfully with a hopper weight (HW) or returning anerror indicating that the hopper was too unstable for a measurement tohave been taken.

At the beginning of the process, the variables used for temporarystorage and loop control are initialized (S60) and a sampled digitalvalue, L, is taken from load cell 12 (S61). As should be apparent fromthis description, the processes of FIGS. 4-8 are equally applicable tocoin accounting using a drop box, with the main difference being thatload cell 12(a) is sampled instead of load cell 12. The sampled value Lis stored as a reference reading R (S62), and a main loop is entered.

In the main loop, the load cell is again sampled (S63) to obtain a newvalue for L. If the absolute value of the difference between L and thereference reading R is less than a variance limit, V, then the sampledvalue L is added to an accumulator (HW) and a loop counter (I) isincremented (S65). CPU 106 then pauses for a predetermined delay periodof T1 ms (S66) and then loops back to step S63 to take another reading.This continues until a predetermined number, C₋₋ SAMP, of readings hasbeen taken. Once C₋₋ SAMP samples have been taken and accumulated, thevalue in the accumulator (HW) is divided by C₋₋ SAMP (S68), to yield ahopper weight. In a preferred embodiment, the digital values L and R areintegers ranging from zero to 16,383, the variance threshold V is 120,T1 is 100 ms and C₋₋ SAMP=40.

If the absolute value of the difference between L and R is greater thanor equal to V, indicating too much variance between a sampled weight anda reference weight, the reference weight is adjusted by an incrementVSTEP (S69). More specifically, R is adjusted so that the absolute valueof the difference between L and R is reduced by VSTEP, i.e., if R isgreater than L by more than V, R is reduced by VSTEP and if R is lessthan L by more than V, R is increased by VSTEP. In a preferredembodiment, VSTEP=10.

Following the adjustment of R, the loop counter (I) and the accumulator(HW) are zeroed (S70) and an unstable reading counter, U, isincremented. If the unstable reading counter U is not greater than amaximum UMAX, then CPU 106 reenters the main loop just before step S66.Otherwise, if U is greater than UMAX, U is reset to zero and an errorcount (ERRCNT) is incremented (S72). If the error count is greater thana maximum error value (ERRCNT>MAXERR), the hopper weight process endsand an error indication is returned. Otherwise, CPU 106 reenters themain loop just before step S66. In a preferred embodiment, UMAX=40 andMAXERR=4. Also, in a preferred embodiment, as instability is detected,the operator is provided with an indication, such as a display "UNST",to indicate that instability is being detected, thereby giving theoperator the opportunity to eliminate the source of instability while areading is being taken. Assuming a valid hopper weight reading isobtained, this can be used in the calibration process shown in FIG. 6.

FIG. 8 shows the process of taking a reading, which results in either acoin count C being returned or an error indication being returned. Atthe outset of this process an accumulator (HW) and a loop counter (notshown) are initialized. In the main loop (shown as steps S81, S82, S83)a load cell is sampled to obtain a value L, CPU 106 delays for T2 ms,and the sampled value L is added to the accumulator (HW). This looprepeats until N₋₋ SAMP samples are taken. In a preferred embodiment, T2is 200 ms and N₋₋ SAMP=30.

Once N₋₋ SAMP samples are taken, the accumulator (HW) is divided by N₋₋SAMP (S85) and the resultant hopper weight (HW) is compared to thehopper tare weight (S86). If the hopper weight HW is less than the tareweight TW, an error signal is generated (S87), otherwise a coin count Cis calculated according to the formula:

    C=ROUND((HW-TW)/CW).

Of course, other suitable formulae can be used. The hopper weightreading process of FIG. 8 is less interactive and less error-correctingthan the hopper-weight reading process of FIG. 3, since the formergenerally occurs when the slot machine is not open and an unreliablereading can be discarded without ill effects, whereas the latter processprovides tare weight and per coin weights which cannot be as easilydiscarded.

Thus, in the manner described above, a hopper is weighed periodicallyand that weight is used, combined with an automatically determined percoin weight, to determine a number of coins in the hopper. In onespecific use of the coin count, coins are counted just before a hopperdoor is opened and then counted again after the hopper door is closedand this difference is compared to an authorized difference to determineif unauthorized removal of coins from the hopper while the hopper doorwas open occurred. One application of this system includes a centralizedslot machine control system, from where a trusted employee can monitorthe opening and closing of each slot machine door, as well as a currentinventory of the coins in the hopper and/or drop box of each slotmachine. The necessary information can be communicated from the slotmachines to the centralized slot machine control system throughdedicated communication lines running from each slot machine or can beprovided by the above described data pin system.

The above description is illustrative and not restrictive. Manyvariations of the invention will become apparent to those of skill inthe art upon review of this disclosure. Merely by way of example, itshould be apparent after reading the above description that noncoindisks or tokens, or even bills or scrip could be accounted for as coinsare, and that the present invention could be used with other gamingmachines or vending machines. It should also be apparent that the datapin system described above can be replaced with a hard-wired slotmachine communications network connection, wireless links, optical or RFcommunications links, or the like. The scope of the invention should,therefore, be determined not with reference to the above description,but instead should be determined with reference to the appended claimsalong with their full scope of equivalents.

What is claimed is:
 1. A method of coin theft detection in a gamingmachine, comprising the steps of:a first step of weighing coins in acoin hopper of the gaming machine, thereby measuring a first weight; afirst step of calculating a number of coins in the coin hopper based onthe first weight, resulting in a first count; allowing access to thecoins in the coin hopper; a second step of weighing coins in the coinhopper of the gaming machine, thereby measuring a second weight; asecond step of calculating a number of coins in the coin hopper based onthe second weight, resulting in a second count; and setting an alarm ifthe second count is less than the first count minus an authorized numberof removed coins.
 2. The method of claim 1, wherein the coins are tokensexchangeable for value.
 3. The method of claim 1, wherein the firstweighing step is performed at a time when the coin hopper is securewithin the gaming machine and the second weighing step is performed at atime when the coin hopper is secure within the gaming machine, themethod further comprising a step of detecting who has access to the coinhopper during a period in which the coin hopper is not secure betweenthe time the first weighing step is performed and the second weighingstep is performed.
 4. The method of claim 3, wherein access to the coinhopper is limited by use of an electronic key for opening a door of thegaming machine, the method further comprising the step of reading theelectronic key and recording an electronic key identifier.
 5. The methodof claim 1, further comprising the steps of:dropping an overflow numberof coins from the coin hopper into a drop box when a level of coins ator above a drop threshold is detected in the coin hopper; weighing coinsin the drop box, thereby determining a drop box coin weight; calculatinga number of coins in the drop box from the drop box coin weight,resulting in a drop box count; and adding the drop box count to thefirst or second count to determine a total coin count.
 6. The method ofclaim 1, wherein the first and second steps of weighing coins are stepsof weighing coins of known unit weight.
 7. The method of claim 1,wherein the first and second steps of weighing coins are steps ofweighing coins and the coin hopper.
 8. The method of claim 1, whereinthe steps of weighing coins comprise the substeps of:measuring anacceleration of the coin hopper relative to the gaming machine; andmeasuring a distortion of a cantilever beam which is distorted by theweight of the coin hopper and the coins therein when the acceleration ofthe coin hopper relative to the gaming machine is essentially zero or isa known acceleration.
 9. A method of securing a gaming machine fromunauthorized removal of coins from a coin hopper in the gaming machine,comprising the steps of:detecting a door being opened; substantiallysimultaneously with the door being opened or before, measuring a firstnumber of coins in the coin hopper by weight; detecting the door beingclosed; measuring a second number of coins in the coin hopper by weightafter the closing of the door is detected; and determining a differencein coin count by subtracting the first count from the second count andelectronically reporting the difference to a theft control system. 10.The method of claim 9, further comprising the step of adjusting thedifference to account for authorized coin removals.
 11. The method ofclaim 9, further comprising a step of setting an alarm when thedifference is greater than zero.
 12. The method of claim 11, wherein thestep of setting an alarm is a step of setting a flag in a field of a rowof a data table associated with the gaming machine in which thedifference is detected.
 13. A gaming machine comprising:a plurality ofcoin containers housed within an interior area of the gaming machine; aswitch that detects entry into the interior area of the gaming machineand subsequent exit out of the interior area of the gaming machine; aplurality of coin container sensors operably connected, respectively, tosaid plurality of coin containers to detect a weight of any contents ofsaid plurality of coin containers; means for recording a weight producedby said plurality of coin container sensors in response to detection ofentry into the interior area by said switch; means for recording aweight produced by said plurality of coin container sensors in responseto detection of exit of the interior area by said switch; means forcomparing the weight produced by said plurality of coin containersensors in response to detection of entry with the weight produced bysaid plurality of coin container sensors in response to detection ofexit.
 14. A method for detecting theft or fraud in a gaming machinecomprising the steps of:A. detecting entry into the interior area of thegaming machine wherein a coin container is housed; B. recording a weightof the coin container upon detecting entry to produce an entry weight;C. detecting exit out of the interior area of the gaming machine; D.recording a weight of the coin container upon detecting exit to producean exit weight; and E. comparing the entry weight with the exit weightto produce an actual net change wherein the actual net change reflectswhether there was a theft or fraud.